This invention relates to an endoscope tube system including an elastically bendable section which contains individual members spaced in an axial manner behind one another.
In order to achieve the bending movement of the elastically bendable section, known endoscope tube systems of this type include tension cables which are guided through openings in the circumferential area of the individual members. This type of a flexible endoscope tube is described, for example, in German Patent document DE 26 18 732 B2. In this case, the individual members are connected with one another in an articulated manner.
These known endoscope tube systems can only be taken apart at great costs, if at all. In addition, the passage of the tension cable through the individual members is relatively susceptible to disturbances and, because it is difficult to take apart, the whole tube arrangement can only be cleaned at high costs which makes in particular the articulated connection of the individual members and the passage areas of the tension cable susceptible to dirt.
In U.S. Pat. No. 5,018,506, a flexible rod is described which can be used for endoscopes as a measuring instrument indicator or the like. The flexible rod has a longitudinally extending spring band which is curved in its relaxed condition. The rod interior may be acted upon in a pneumatic or hydraulic manner by means of pressure, whereby the rod can be moved from the curved position resulting from the spring band, into positions with a smaller bending angle, and finally into positions having an opposite bend.
From U.S. Pat. No. 4,934,340, a bending control arrangement is known for catheters, endoscopes and the like. In an elastically bendable section of the catheter, the arrangement contains an axially extending stabilizing spring band and opposite thereto, an axially extending, contractible band. In this case, the contractible band consists of a nickel titanium alloy and is shortened in the axial direction when electric current flows through it. The stabilizing spring band and the contractible band are mechanically connected with one another by way of one or several connecting members.
There is therefore needed an endoscope tube system which, with only minimal costs, can be taken apart into individual components. In particular, the individual components are also easy to clean. In addition, there is needed an endoscope tube system which is not very susceptible to dirt, can be used in multiple manners, and is not very susceptible to disturbances. There is also needed an endoscope tube system which, in addition to being easily taken apart, also permits the adjustability of the elastically bendable section at different bending angles with a respective comparatively high stiffness.
These needs are met according to the present invention by an endoscope tube system including an elastically bendable section which contains individual members axially spaced behind one another, an axially extending stabilizing spring band on which each individual member is fixed on a circumferential area, and an axially extending tension spring band which is situated opposite the stabilizing spring band and can be axially moved relative thereto, and on which only the most forward of the individual members is fixed. At least one of the two spring bands extend in a curved manner in the relaxed condition. The elastically bendable section is bendable in the direction opposite to this curvature through the axial movement of the tension spring band.
The spring band arrangement replaces the previously known tension cable arrangements of the elastically bendable section. In this case, the individual members are fixed at the stabilizing spring band and therefore do not have to be connected with one another by complicated joints or articulations. The axial mobility of the tension springband allows for a bending away of the elastically bendable section in a direction which imitates the behavior of the human hand. At least one of the spring bands is arranged in a prestressed manner against its natural curvature. In this case, the resulting, transversely acting tension force counteracts in a spring-elastically restoring manner the curvature of the elastically bendable section which can be caused by a pulling on the tension spring band. At the same time, this prestress has the effect that the tension spring band remains reliably elastically pressed against each individual member without being connected with these members, with the exception of the last individual member. The susceptibility to disturbances of the tension cable passages extending through the bores, which exists when tension cables are used, as well as the susceptibility to disturbances of the individual member joints, is avoided in the case of this design according to the invention. In addition, the individual members can be constructed as relatively smooth parts which are therefore not very susceptible to dirt and are easy to clean.
An advantageous further embodiment of the present invention also allows for the possibility of being able to adjust the elastically bendable section so as to be very resistant to bending also in the intermediate positions between the linear course and the maximal bending. For this purpose, a stiffening sleeve tube is pushed, by means of an end area, in the respective desired length over a correspondingly long, rearward portion of the elastically bendable section. The stiffness of the stiffening sleeve tube is selected such that the portion of the elastically bendable section enclosed by its end region adapts to the shape of the enclosing tube end region which, in particular, may be linear. This achieves an effective shortening of the remaining part of the elastically bendable section which in each case may also be changed in its curvature by using the tension spring band. As a result of this shortening and the additional stiffness of the stiffening sleeve tube, an arrangement with high stiffness is also obtained in any bending position in the bending direction.
An advantageous further embodiment of the present invention allows for the possibility of lifting the elastically bendable section, including the stabilizing and tension spring band, in a simple manner off the tube lengthening. The tube lengthening includes at least one tube which is clearly more resistant to bending than the elastically bendable section. This has the effect that it is easier to disassemble the endoscope tube system. It is possible to clean the elastically bendable section separately from the components of the tube lengthening. For this purpose, the connection member is provided on the rearward end of the elastically bendable section. The connection member can be detachably mounted on the forward end of the tube lengthening.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.